Does anyone know how to change this static.222.222.222.222.clients.your-server.de to be MYDOMAIN.COM? I read in some articles that big services such Gmail, Hotmail... take that part as important when they do filter mails.

Re: DKIM - Not checked in header of recipient

but when I sent mail from my domain, in header of recipient mail I don't see any clue that DKIM is checked at all. Any idea?

"Any idea?" part should look like this question:

If is everything all right with configuration of DKIM on my server and on DNS record, how to setup that my server send mail with DKIM, then Google check that key and to put him in header of receipient mail?